Color selection electrode suspension system with bimetal structures having orthogonal deflection components

ABSTRACT

This disclosure depicts suspension systems and methods for supporting a color selection electrode adjacent the faceplate portion of a color cathode ray tube envelope. The suspension systems disclosed each comprise a plurality of suspension devices spaced around the periphery of the electrode for mechanically coupling the electrode to the tube envelope through bimetal means. In a preferred embodiment the bimetal means is constructed and supported such that, when heated, it deflects to produce two components of deflection motion - a first component which causes the suspended electrode to be displaced along the tube axis toward the tube faceplate to provide Q compensation during normal tube operation, and a second component which acts to at least partially compensate for expansion of the mask in a plane orthogonal to the tube axis so as to minimize build-up of expansion induced stresses in the suspension system and in the mask. A number of embodiments of the described mask suspension devices and included bimetal means are disclosed. An electrode suspension method is also disclosed.

United States Patent [191 Sedivy COLOR SELECTION ELECTRODE SUSPENSION SYSTEM WITH BIMETAL STRUCTURES HAVING ORTHOGONAL DEFLECTION COMPONENTS [75] Inventor: Stanley J. Sedivy, Chicago Ridge,

Ill.

[73] Assignee: Zenith Radio Corporation, Chicago,

Ill.

[22] Filed: Dec. 12, 1973 [2]] Appl. No.: 424,018

[52] US. Cl 313/405; 29/2515 [51] Int. Cl H01] 29/02; HOlj 29/08 [58] Field of Search 313/85 J, 92 B, 92 P, 92 D,

[56] References Cited UNITED STATES PATENTS 3,449,6ll 6/l969 Schwartz et a1. 313/238 X 3,548,235 l2/l970 Driedijk et al. 313/292 X 3,573,527 4/197] Hakkenscheid et al. 3l3/292 X Primary ExaminerRobert Segal Attorney, Agent, or Firm-John H. Coult July 8,1975

[57] ABSTRACT This disclosure depicts suspension systems and methods for supporting a color selection electrode adjacent the faceplate portion of a color cathode ray tube envelope. The suspension systems disclosed each comprise a plurality of suspension devices spaced around the periphery of the electrode for mechanically coupling the electrode to the tube envelope through bimetal means. In a preferred embodiment the bimetal means is constructed and supported such that, when heated, it deflects to produce two components of deflection motion a first component which causes the suspended electrode to be displaced along the tube axis toward the tube faceplate to provide Q compensation during normal tube operation, and a second component which acts to at least partially compensate for expansion of the mask in a plane orthogonal to the tube axis so as to minimize build-up of expansion induced stresses in the suspension system and in the mask. A number of embodiments of the described mask suspension devices and included bimetal means are disclosed. An electrode suspension method is also disclosed.

19 Claims, 13 Drawing Figures COLOR SELECTION ELECTRODE SUSPENSION SYSTEM WITH BIMETAL STRUCTURES HAVING ORTIIOGONAL DEFLECTION COMPONENTS CROSS-REFERENCE TO RELATED APPLICATION This application is related to, but in no way dependent upon, copending applications Ser. No. 395,334, filed Sept. 7, 1973; Ser. No. 395,106, filed Sept. 7, 1973; and Ser. No. 285,985, filed Sept. 5, 1972, all assigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION This invention relates in general to suspension systems for supporting a color selection electrode in a cathode ray tube.

Conventional shadow mask-type color tubes have a color selection electrode in the form of a shadow mask assembly which comprises a rigid frame upon which is welded a thin, spherically-shaped mask having a pattern of electron-transmissive apertures formed therein. The mask assembly is suspended in the tube by a set of bimetal springs, usually three in number, which are welded to the mask frame, and which engage studs extending inwardly from the tube front panel.

Such prior art mask suspension systems have a number of drawbacks. During manufacture of a color cathode ray tube, the mask and its suspension system are subjected to thermal cycling through relatively high temperatures (500600C, for example) in order to stress relieve these components and the front panel. The thermal cycling operation has the effect of reducing the spring rate of the bimetal springs. In order that the bimental springs will have an ultimate spring rate effective to produce a desired loading force on the mask after thermal cycling, an initial spring rate must be selected which is substantially greater than the desired ultimate value. However, the use of such high rate bimetal springs results in the imposition of undesirably high loading forces on the mask and its suspension system during thermal cycling of the tube.

In order to minimize any such overloading of mask and mask suspension system which occurs during the stress relieving operation, it is necessary that bimetal springs be chosen which have an undesirably low ultimate spring rate. Restated, the mask suspension system must have built into it an undesirably high degree of resiliency in order that the suspension system and mask may be able to withstand the extreme temperatures encountered during thermal cycling of the tube. However, as a result of the use of a low spring rate suspension system, the mask is prone to vibration, with resultant degradation of the displayed cathode ray tube images.

The mask suspension system and method of the present invention have general applicability, but are particularly useful for suspending directly on the faceplate of a cathode ray tube a light-weight, frameless mask of novel construction, described below. This novel mask is flexible in torsion and is supported on the tube faceplate so as to conform very closely to the contour of the faceplate. Conventional mask suspension systems are completely unsuitable for mounting a light-weight, frameless, flexible shadow mask of the type to be described since, inter alia, such masks are structurally weak and would experience severe distortion during thermal cycling of the tube and during normal tube operation.

Prior Art US. Pat. Nos. 3,497,746; 3,529,199; and 3,548,235

British Pat. Nos. 1,278,633; 1,278,634; and 1,278,635

OBJECTS OF THE INVENTION It is a general object of this invention to provide an improved suspension system and method for supporting a color selection electrode in a color cathode ray tube.

It is a less general object of this invention to provide a suspension system and method for a color selection electrode which minimizes the build-up of stresses in the electrode and in the suspension system during the high temperature stress-relieving operation encountered during tube manufacture, and during normal tube operation, and which also provides 0 compensation during nonnal tube operation.

It is still another object to provide improved bimetallic structures having deflection characteristics effective to achieve the afore-stated objects.

It is another object of this invention to provide an improved suspension which is especially useful for suspending directly upon the faceplate of a color cathode ray tube a novel color selection electrode in the form of a light-weight, frameless shadow mask which would be particularly susceptible to distortion and damage as a result of the high temperature conditions encountered during tube manufacture and in normal tube operation.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the present invention which are believed to be novel and unobvious are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompany ing drawings, in which:

FIG. I is a perspective view of a novel color cathode ray tube as seen from the rear, with a portion of the envelope cut away to reveal a part of a shadow mask suspension system implementing the principles of this invention',

FIG. 2 is a partially sectioned fragmentary elevational view of the FIG. 1 tube, showing particularly a shadow mask and a part of its suspension system;

FIG. 3 is a perspective view of a mask suspension device constituting a component of the suspension system illustrated in FIGS. 1 and 2;

FIG. 4 is a perspective view of a bimetal member shown in FIGS. 1-3;

FIGS. 5-7 illustrate alternative bimetal members which may be substituted for a bimetal member constituting part of the FIGS. 1-4 suspension system;

FIG. 8 is a schematic side elevational view, partially sectioned, of a mask suspension device constructed according to this invention and incorporating the bimetal member shown in FIG. 7;

FIG. 9 is a plan view of the mask suspension device shown in FIG. 8;

FIG. 10 illustrates yet another bimetal member useful in mask suspension devices according to this invention;

FIGS. 11 and 12 depict a bimetal member and a suspension device embodying the member which are constructed according to this invention but operating on a different principle than the bimetal members and suspension devices illustrated in FIGS. 1-10; and

FIG. 13 illustrates still another embodiment of the invention for use with a flanged faceplate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This application is directed to the provision of a suspension system for supporting a color selection electrode adjacent the faceplate portion of a color cathode ray tube envelope. The invention has applicability to the suspension of shadow masks and other color selection electrodes in general; however, for reasons which will be pointed out in detail below and which have been discussed briefly above, it is especially useful as applied to the mounting of a novel light-weight, frameless mask of the nature described and claimed in copending application Ser. No. 395,334. The suspension systems of this invention may include three or more suspension devices, but as applied to the afore-described novel mask, preferably includes four suspension devices, one at each corner of the mask. By this arrangement of suspension devices, the mask is permitted to flex in torsion and to conform to the contour of the faceplate. The general concept of a flexible, light-weight, frameless mask which is supported at its corners so as to permit conformance to the contour of a cathode ray tube faceplate is described and claimed in the above-identified copending application Ser. No. 285,985.

A preferred implementation of the principles of this invention is disclosed in FIGS. 1-4. However, before engaging a detailed description of the FIGS. 1-4 preferred embodiment, the general principles of this invention will be explained.

As discussed at some length above, the thermal expansion of a color selection electrode has a number of implications on tube manufacture and tube operation. During the conventional stress relieving operation conducted during tube manufacture, a shadow mask expands to a greater extent than the supporting tube envelope, for example by a differential of 40 mils or more, with a consequent imposition of high loading forces on the suspension system and on the mask.

Also, during normal operation of an assembled tube, as a result of the heating effects of the electron beams, the color selection electrode expands. In the case of a color selection electrode of the aperture mask type, expansion causes the hole pattern to enlarge radially and thus the hole-to-hole spacing to increase. Expansion of the mask aperture pattern would thus result in a misregistration between the mask apertures and the associated phosphor elements unless some compensation for this effect were made.

It is well known to compensate for the described thermally induced beam spot-phosphor element misregistration by causing the mask as it is heated to be moved closer to the screen in proportion to the degree of heating. The distance between the screen and the mask is commonly termed the distance; the described compensation is commonly termed Q compensation.

The conventional approach to accomplishing 0 compensation is to use mask suspension devices which include a bimetal spring in the form of a planar member having two coplanar edge-bonded strips of metals having different coefficients of thermal expansion. The bimetal springs are mounted such that they lie in a plane generally parallel to the tube axis, hereinafter termed the Z axis. Upon heating of the mask (and, by conduction, the bimetal springs) by the electron beam, the bimetal springs deflect in their own plane, and thus in the Z direction, so as to translate the suspended mask a distance toward the phosphor screen appropriate to achieve the described 0 compensation. Movement of the mask toward the screen brings the aperture pattern back into registration with the p osphor element pattern.

It has not been the practice of tube makers to attempt to compensate for the effects of thermal expansion of the mask in the plane perpendicular to the Z axis, hereinafter termed the X-Y plane, other than the described Q compensation. As noted, however, expansion of the mask introduces undesirably high loading stresses on the mask suspension system and on the mask itself. Conventional tubes employ a frame to support the mask which is sufficiently rigid to with tand the aforedescribed stresses introduced by thermal expansion of the mask. However, a light-weight, frameless mask of the nature discussed would be subiect to distortion upon such thermal expansion thereof.

It is a stated object of this invention to provide a sus pension system for color selection electrodes which is effective to achieve not only 0 compensation, but which is also effective to at least partially, and desirably wholly, compensate for the effects of thermally induced expansion of the electrode on the electrode and on its suspension system.

In accordance with a preferred execution of this invention a suspension system is provided which comprises a plurality of electrode suspension devices for mechanically coupling the color selection elec rode through bimetal means to the tube envelope. The bimetal means, when heated, deflects such as to produce two components of deflection motion a first component which causes the suspended mask to be displaced toward the faceplate in the Z direction for 0 com pensation, and a second component which acts to at least partially compensate for thermal expansion of the mask in the X-Y plane so as to minimize build-up of expansion-induced stresses in the suspension system and in the electrode. As used herein, the term component of deflection motion is intended to mean a component of motion of one or more points on a bimetal member, when heated, which are free to move relative to one or more points of the member which are anchored. In the interest of ease of discussion, this latter compensation or partial compensation will be referred to as an X-Y plane stress compensation.

The described two components of deflection motion may be achieved in accordance with this invention by any of a number of different approaches. A first and preferred approach is to employ bimetal means which has two modes of deflection a first mode in a predetermined plane, which may be the plane of the bimetal means, and a second mode out of the said plane. The b metal means is supported within the suspension device such that the two modes of defl ction are effectively translated into the said two components of deflection'motion. Bimetal means implementing this approach and structures embodying such bimetal means are contained in the preferred FIGS. 1-4 execution of the invention.

FIGS. 14 illustrate a color cathode ray tube incorporating a suspension system for a color selection electrode (here shown as a shadow mask) which implements the principles of this invention. The tube 10 is depicted as having an envelope comprising a funnel l2 sealed to a generally rectangular, skirtless front panel or faceplate 14. The tube 10 includes a light-weight, frameless, torsionally flexible, generally rectangular shadow mask 16 of novel character, as described in detail and claimed in the referent copending application Ser. No. 395,334. Briefly, the shadow mask 16 in its illustrated form comprises a sheet of electrically conductive material having a curved central portion 18 which has formed therein a pattern of electron-transmissive apertures 20. The mask includes a strengthening channel 22 surrounding and joined with the central portion 18.

The mask 16 has a skirt 24 of generally constant depth surrounding and joined with the channel 22. The skirt 24 includes a forwardly directed, outwardly flared body portion terminating in a leading edge portion 28. As described in detail in the referent copending application, the configuration of the strengthening channel 22 of the skirt 24 is such as to maximize the strength of the mask and to shield, to the maximum degree possible, the phosphor screen 28 on the inner surface of the faceplate 14 from stray or overscanned electrons from the electron beams. The flared body portion of the skirt 24 has formed along each side a plurality of strengthening rib elements 30.

This invention is directed to the provision of a suspension system for supporting a color selection electrode such as mask I6 which includes a plurality of mask suspension devices 31, four in number in the application being described. The devices 31 are each illustrated as comprising mask-mounted means, shown in the form of a bracket including a bimetal member 32, described in detail below, which is affixed at a corner of the mask 16 by a pair of arms 34, 36 which bridge the corner of the mask and are welded thereto on opposite sides of the corner.

The bimetal mem ber carries one leg of a reverse bent leaf spring 38, on the opposed leg of which is mounted a conically tapered lug 40. Each device 31 includes a stud 42 anchored to the faceplate 14. The stud 42 may be embedded in the faceplate 14 in a manner well known in the art, or bonded thereto. The stud 42 integrally defines an opening 44 for receiving and seating the lug 40 on the spring 38.

The spring 38 is preferably of a type, as shown, which has the property of providing a force-deflection characteristic which is ideally constant, but at least less than linear.

As pointed out in detail in the referent copending application Ser. No. 285,985 in a mask suspension system according to that invention, mask suspension devices are provided at the four corners of the mask, however, only three of the four suspension devices locate the mask in X, Y and Z coordinates. Assuming the tube axis to represent the Z axis, all four of the devices 10- cate the mask in the Z coordinates, i.e., relative to the faceplate whereas only three of the four devices fix the position of the mask in the X and Y coordinates, i.e., parallel to the faceplate. To this end, one of the mask suspension devices 31 would have an opening 44 which is elongated in the X-Y plane so as to permit the mask 16 to float in the X-Y plane at a fixed spacing from the faceplate 14.

The bimetal member 32 and its supporting structure will now be described in detail. Reference may be had particularly to FIG. 4. The FIG. 4 bimetal member may be described in general as comprising efi'ective first and second orthogonally acting bimetal pairs. A first bimetal pair deflects such that it has a primary component of deflection motion in the first plane, the second bimetal pair deflects such that it has a primary component of deflection out of that plane.

The FIG. 4 bimetal member 32 is illustrated as comprising a one-piece, sheet-like element having four strip metal components bonded together. A first component 46 and a second component 48, constituting the first bimetal pair, have different coefficients of thermal expansion and are edge-coupled in the primary plane of the element, shown as the vertical plane in FIG. 4, such that upon heating of the element the pair tends to deflect the member in the said plane. Third and fourth metal components 50, 52 have different coefficients of thermal expansion, which are preferably different also from the coefficients of expansion of the first and second metal components 46, 48, and are face-coupled in the thickness dimension of the element. The third and fourth metal components 50, 52, when heated, cause a horizontal deflection of the element (in FIG. 4). Whereas other geometric arrangements of the bimetal components are within the compass of this invention, in the illustrated FIGS. l-4 embodiment the third and fourth components 50, 52 are embraced by the first and second components 46, 48.

In the illustrated preferred FIGS. l-4 embodiment, the first and second components 46, 48 are angled out of the vertical plane, here shown at an angle approximately It has been found that by 90 structuring the bimetal member into a channel-like shape, greater control of the deflection characteristics of the member can be attained.

The absolute and relative length 1, height 11 and width w of the member 32 and the absolute and relative coefficients of thermal expansion thereof may be varied to achieve a predetermined deflection characteristic of the member.

In operation, the bimetal element deflects with the afore-described two components of deflection motion. The resultant deflection vector is designated D in FIG. 4. The first component, which is effective to achieve 0 compensation, is designated AZ in FIG. 4; the second component, which is effective to achieve the described X-Y plane stress compensation, is designated AX-Y plane in FIG. 4.

In the illustrated preferred embodiment, the first strip metal component 46 may be composed of a high expansion stainless steel; the second component may be composed of invar; the third and fourth components may be composed of stainless steel and invar respectively. The third and fourth components are preferably face-bonded by conventional bonding techniques. The first and second components are preferably edgebonded to the third and fourth components by conventional edge bonding techniques.

FIGS. 58 illustrate a number of alternative embodiments of bimetal members constructed according to this invention which, like the FIGS. 1-4 bimetal member 32, provide simultaneously two modes of thermally induced deflection an intra-planar mode and an extraplanar mode. Each of these alternative bimetals may be substituted directly for the FIGS. 1-4 bimetal member 32 in a suspension device like that shown in FIGS. 1-4.

The FIG. 5 bimetal member 54 is similar to the FIGS. I-4 bimetal member 32 except that the member 54 is completely planar, having the first and second metal components 56, 58 edge-coupled coplanarly with the third and fourth metal components 60, 62. The FIG. 5 bimetal member 54 offers freedom to control the absolute and relative width w of the first, second and collective third and fourth components 56, 58, 60, 62 and the absolute and relative coefficients of thermal expansion thereof in order to select desired deflection characteristics of the member 54.

FIG. 6 depicts another bimetal member variant in which the third and fourth metal components 68, 70 have a cumulative thickness which is greater than the thickness of the first and second components 64, 66.

FIG. 7 depicts a bimetal member 72 which represents another embodiment which is preferred from the overall standpoint of performance and economy.

I have discovered that the bimetal member 72 may be a conventional mask suspended spring of the abovediscussed edge-bonded strip bimetal type. Each spring, when heated, deflects not only in its own plane, as intended, but also simultaneously deflects out of its own plane. This extraplanar deflection mode is, I have found, due to the geometry of the edge weld structure which, as formed by conventional edge-bonding techniques is asymmetrical about a medial length-widthexploding cross-sectional plane through the spring (shown as the E-F plane in FIG. 7). As described in detail below, it is a method of this invention to employ this discovered effect to the end of achieving the aforedescribed X-Y plane stress compensation.

FIGS. 8 and 9 illustrate a mask suspension device 74 incorporating a bimetal member 72 of the nature shown in FIG. 7. The device 74 is illustrated as comprising maskmounted means in the form of bimetal member 72 affixed across the corner of the mask 76 by means of a pair of support arms 78, 80 welded to the mask 76 and to the opposite ends of the member 72. A spring 82 is affixed to the center of the bimetal member 72 and has on the distal end thereof a frustoconical lug 84 which is adapted to engage a cylindrical hole 86 in a stud 88 embedded in or otherwise affixed to the tube faceplate 90.

The bimetal member 72 includes a first metal component 92 and a second metal component 94 which are edge-bonded through an intermediate weld structure 96. The weld structure 96 has the property of causing, when the bimetal member is heated, deflection of the member out of its own plane. The weld structure thus effectively acts as a bimetal pair and may be viewed as such. The weld structure comprises a weld material having a different coefficient of thermal expansion from that of either of the metal components 92, 94. The weld material is preferably selected from materials which are compatible with the first and second metal components 92, 94 and which have favorable high temperature properties. Examples of suitable materials are the austentitic class of precipitation hardening steels such as A-286 and semi-austentitic types such as 7PI-I. The hardening of these classes of materials is thermally compatible with the bimetal member pro cessing and tube processing. The first and second components may be a high expansion stainless steel and invar, respectively.

Edge-bonded bimetal springs are conventionally made by welding edge-abutting strips of metals having suitable, different coefficients of thermal expansion such as high expansion stainless steel and invar. The weld material may be an appropriate one of the abovedescribed austentitic or semi-austentitic classes of steel materials or another suitable high yield strength weld material. The welding operation is performed from one side of the abutted strips, resulting in a bead of weld material being formed along the joint line. The bonded strips are then rolled. The rolling operation thins the strip metal stock and flattens the weld material to form a one-piece, flush-sided planar bimetal member. After rolling, the weld structure has a convergent crosssectional configuration, as shown clearly in FIG. 7, which is asymmetrical relative to a lengthwise bisectin g plane, labeled E-F in FIG. 7.

Due to the asymmetry of the weld structure, upon heating of the bimetal member, it will deflect in two modes: l in the plane of the member as a result of the differential coefficients of thermal expansion of the two metal components 92, 94 and (2) out of the plane of the bimetal member as a result of the greater expansion of the member on the side of the E-F plane containing the narrow portion of the convergently cross-sectional weld structure.

These two modes of deflection result in two components of deflection motion of the bimetal member 72 when heated. The two components of deflection motion are revealed clearly by the broken line representations in FIGS. 8 and 9 which depict the position of the suspension device components after heating of the mask 76 and suspension device 74. It can be seen that as the mask 76 expands radially outwardly (as shown with broken lines) the bimetal member 72 deflects downwardly in its own plane, to cause movement of the mask in the Z direction, and simultaneously deflects out of its own plane to accommodate the thermal expansion of the mask. It is noted that the FIGS. 89 embodiment cause the mask 30 to be placed in tension. By this arrangement, when the mask expands during ther mal cycling of the tube during manufacture, or during normal operation of the tube, stresses created in the bimetal member 72 are relieved, rather than augmented. By contrast, in the prior art suspension arrangements, during thermal cycling operations high stresses are introduced in the mask-mounting spring members which place the mask assembly under high compressive loading. Such compressive stressing of the mask during thermal cycling is of particular concern when considered in connection with light-weight, frameless masks of the type with which this invention is particularly use ful.

FIG. 10 depicts a bimetal member 98 representing still another embodiment of the invention combining the economy of the FIG. 7 bimetal member with the high degree of control available with the channelshaped bimetal member 32 of the preferred FIGS. l-4 embodiment. In FIG. 10 first and second components 100, I02 and weld structure 104 have different coefficients of thermal expansion and a general structure as described with respect to the FIGS. 79 embodiment, however the first and second components 100, 102 have angled marginal portions 106, 108.

As in the FIGS. 1-4 bimetal member 32, the length 1, height h and width w of the member 98, as well as the relative and absolute coefficients of thermal expansion of the components 100, 102 may be selected to yield a bimetal member 98 having desired deflection characteristics. Further, the deflection characteristics of the member may also be altered by predetermining the cross-sectional shape of the weld structure 104 the less rectangular (i.e., the more triangular) the crosssectional configuration of the weld structure, the greater will be the deflection of the member 98 for a given thermal excitation.

This invention encompasses a second basic approach to achieving the above-described two components of deflection motion. This second approach involves the use of a bimetal element or member which, when heated, has but a single deflection mode, namely in its own plane. However, the bimetal member is mounted such that the plane of the member is oriented at a pre determined angle relative to the tube axis (the Z axis). The angle is such that the member, when heated, deflects in its own plane but has components of deflection motion effective to achieve both Q compensation and X-Y plane stress compensation.

To further an understanding of this second approach, reference may be made to FIG. 11. FIG. 11 shows a bimetal member 110 which is rigidly held at one end. The member 1 10 is caused to have a predetermined angular orientation, identified by the angle 0, relative to an axis designed Z, which is such that upon deflection of the member 110 in its plane, that is along vector 112 in FIG. 11, a vectorial component of deflection motion 114 is produced which is appropriate for Q compensation. A second vectorial component of deflection motion, shown by the vector 116, is produced in the X-Y plane. The component 116 is such as to achieve the afore-described X-Y plane stress compensation.

H0. 12 illustrates a mask suspension device 118 similar to the FIGS. 7-9 device but implementing the afore-described second approach depicted in FIG. 11 rather than the first described approach as depicted, for example, in the earlier described embodiments. A bimetal member 120 is shown as comprising two coplanar edge-bonded strips 122, 124 of metals having different coefficients of thermal expansion. Arms 126, 128 support the bimetal member 120 at a predetermined angle 6 relative to the tube axis (the Z axis), which is such, when taken with the different coefficients of thermal expansion of the strips 122, 124, to produce the appropriate two components of deflection motion necessary to achieve compensation and X-Y plane stress compensation.

The invention is not limited to the particular details of construction of the embodiments depicted and other modifications and applications are contemplated. Certain changes may be made in the above-described methods and apparatus without departing from the true spirit and scope of the invention herein involved. For example, whereas each of the above-described embodiments has been depicted in a tube havinga skirtless faceplate, the principles of the invention may be implemented in tubes of the conventional type having a flanged faceplate or front panel. FIG. 13 illustrates an embodiment of the invention similar to the F105. 1-3 embodiment but having an apertured spring 130 affixed on a bimetal 132 for engaging a stud 134 embedded in the corner ofa flange 136 on a front panel 138.

As another example, whereas in each of the abovedepicted embodiments the bimetal member is mechanically coupled at its center to the tube envelope and the deflection motion produced when the member is heated is developed at both extremities of the member, it is within the compass of this invention to couple a bimetal member at its ends, one end to the color selection electrode and the other to the tube envelope. Other bimetal member configurations may be employed consistent with the above-expressed principles of this invention. Suspension devices according to this invention may be employed to support color selection electrodes of types other than the illustrated shadow mask type. it is intended that the subject matter in the above depiction shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A suspension system for supporting a color selection electrode adjacent the faceplate portion of a color cathode ray tube envelope, comprising a plurality of suspension devices disposed at spaced points around the periphery of the electrode for supporting the electrode adjacent to said faceplate portion, each device comprising mask-mounted means affixed to said electrode which retentively engages envelopemounted means affixed to said faceplate portion, said maskmounted means including bimetal means comprising effective first and second orthogonally acting bimetal pairs, said bimetal means reacting, when heated, such that said first bimetal pair produces a deflection of the bimetal means with a primary component of deflection motion to cause the suspended electrode to be displaced toward the faceplate along the central Z axis of the tube for Q compensation, and such that said second bimetal pair produces a deflection of the bimetal means with a primary component of deflection motion in an X-Y plane orthogonal to the Z axis to at least partially compensate for thermal expansion of said X-Y plane and thereby reduce the build-up of expansion-induced stresses in the suspension system and in the electrode.

2. The apparatus defined by claim 1 wherein said bimetal means comprises a sheet-like member having four strip metal components bonded together, a first and second component constituting said first bimetal pair and having different coefficients of thermal expansion and being edge-coupled in the plane of said member such that upon heating of said member, said first and second components produce deflection of the member in the plane of the member, said third and fourth components constituting said second bimetal pair and having different coefficients of thermal expansion and being face-coupled in the thickness dimension of said member such that upon heating of said member, said third and fourth components produce deflection of the member out of the plane of the member.

3. The apparatus defined in claim 2 wherein said four components of said member comprises four bonded metal strips, said third and fourth components being embraced by said first and second components.

4. The apparatus defined by claim 1 wherein said first bimetal pair comprises first and second strip metal components having different coefficients of thermal expansion which are edge-bonded through an intermediate weld structure having a predetermined assymetry relative to a length-extending plane bisecting the member, said weld structure constituting said second effective bimetal pair.

5. The apparatus defined by claim 3 wherein said first and second components are arranged mutually parallel but have at least a portion thereof orthogonal to said third and fourth components such that said bimetal means has a channel-like configuration.

6. A suspension system for supporting a light-weight, frameless, rectangular color selection electrode adjacent the faceplate portion of a color cathode ray tube envelope, comprising four electrode suspension devices, one at each corner of the electrode, for supporting the electrode adjacent to said faceplate portion, each device comprising mask-mounted means affixed to said electrode which retentively engages envelopemounted means affixed to said faceplate portion, said mask-mounted means including bimetal means having at least two edge-bonded components, said bimetal means, when heated, deflecting to produce two components of deflection motion a first component which causes the suspended electrode to be displaced toward the faceplate along the central Z axis of the tube for O compensation and a second component which at least partially compensates for thermal expansion of said electrode in an X-Y plane orthogonal to the Z axis so as to reduce build-up of expansion-induced stresses in the suspension system and in the electrode.

7. The apparatus defined in claim 6 wherein said bimetal means comprises effective first and second orthogonally acting bimetal pairs, said first bimetal pair producing a deflection of the bimetal means such that it has a primary component of deflection motion in the Z direction, said second bimetal pair producing a deflection of a bimetal means such that is'has a primary component of deflection motion in the X-Y plane.

8. The apparatus defined in claim 7 wherein said himetal means comprises a one-piece, sheet-like member having four strip metal components bonded together, a first and second component constituting said first bimetal pair and having different coefficients of thermal expansion and being edge-coupled in the plane of said member such that upon heating of said member, said first and second components produce deflection of the member in the plane of the member, said third and fourth components constituting said second bimetal pair and having different coefficients of thermal expansion and being face-coupled in the thickness dimension of said member such that upon heating of said member, said third and fourth components produce deflection of the member out of the plane of the member.

9. The apparatus defined in claim 8 wherein said four components of said member comprise four discrete, mutually bonded metal strips, said third and fourth components being embraced by said first and second components.

10. The apparatus defined in claim 7 wherein said first bimetal pair comprises first and second strip metal components having different coefficients of thermal expansion which are edge-bonded through an intermediate weld structure having a predetermined assymetry relative to a length-extending plane bisecting the member, said weld structure constituting said second effective bimetal pair.

11. The apparatus defined in claim 9 wherein said first and second components are arranged mutually parallel but have at least a portion thereof orthogonal 12 to said third and fourth components such that said himetal means has a channel-like configuration.

12. The apparatus defined in claim 6 wherein said device each comprise means for supporting said bimetal means which includes separate spring means aflixed to said bimetal means.

13. The apparatus defined in claim 12 wherein said spring means has a substantially constant stress vs. strain characteristic.

14. The apparatus defined in claim 6wherein said bimetal means comprises two coplanar, edge-bonded strips of metals having different coefficients of thermal expansion, said devices each including means for supporting said bimetal means with the plane of each of said bimetal means oriented at a predetermined angle relative to said 2 axis such that said bimetal means, when heated, deflects in its own plane to produce said two components of deflection motion.

15. A bimetal member for supporting a color selection electrode in a color cathode ray tube, comprising effective first and second orthogonally acting bimetal pairs, said first bimetal pair deflecting, when said member is heated, to produce in said member a primary component of deflection motion in a predetermined plane through the member, said second bimetal pair deflecting, when said member is heated, to produce in the member a primary component of deflection motion out of said plane.

16. The apparatus defined by claim 15 wherein said bimetal member comprises a one-piece. sheet-like planar element having four strip metal components bonded together, a first and second component constituting said first bimetal pair and having different coefficients of thermal expansion and being edge-coupled in the plane of said element such that upon heating of said element, said first and second components produce deflection of the element in the plane of the element. said third and fourth components constituting said second bimetal pair and having different coefficients of thermal expansion and being face-coupled in the thickness dimension of said element such that upon heating of said element, said third and fourth components produce deflection of the element out of the plane of the element.

17. The apparatus defined by claim 16 wherein said four components of said element comprises four discrete, mutually bonded metal strips, said third and fourth components being embraced by said first and second components.

18. The apparatus defined in claim 15 wherein said first bimetal pair comprises first and second strip metal components having different coefficients of thermal expansion which are edge-bonded through an intermediate weld structure having a predetermined assymetry relative to a length-extending plane bisecting the member, said weld structure constituting said second effective bimetal pair.

' 19. The apparatus defined by claim 16 wherein said first and second components are arranged mutually parallel but have at least a portion thereof orthogonal to said third and fourth components such that said bimetal means has a channel-likeconfiguration. 

1. A suspension system for supporting a color selection electrode adjacent the faceplate portion of a color cathode ray tube envelope, comprising a plurality of suspension devices disposed at spaced points around the periphery of the electrode for supporting the electrode adjacent to said faceplate portion, each device comprising mask-mounted means affixed to said electrode which retentively engages envelopemounted means affixed to said faceplate portion, said mask-mounted means including bimetal means comprising effective first and second orthogonally acting bimetal pairs, said bimetal means reacting, when heated, such that said first bimetal pair produces a deflection of the bimetal means with a primary component of deflection motion to cause the suspended electrode to be displaced toward the faceplate along the central Z axis of the tube for Q compensation, and such that said second bimetal pair produces a deflection of the bimetal means with a primary component of deflection motion in an X-Y plane orthogonal to the Z axis to at least partially compensate for thermal expansion of said X-Y plane and thereby reduce the build-up of expansion-induced stresses in the suspension system and in the electrode.
 2. The apparatus defined by claim 1 wherein said bimetal means comprises a sheet-like member having four strip metal components bonded together, a first and second component constituting said first bimetal pair and having different coefficients of thermal expansion and being edge-coupled in the plane of said member such that upon heating of said member, said first and second components produce deflection of the member in the plane of the member, said third and fourth components constituting said second bimetal pair and having different coefficients of thermal expansion and being face-coupled in the thickness dimension of said member such that upon heating of said member, said third and fourth components produce deflection of the member out of the plane of the member.
 3. The apparatus defined in claim 2 wherein said four components of said member comprises four bonded metal strips, said third and fourth components being embraced by said first and second components.
 4. The apparatus defined by claim 1 wherein said first bimetal pair comprises first and second strip metal components having different coefficients of thermal expansion which are edge-bonded through an intermediate weld structure having a predetermined assymetry relative to a length-extending plane bisecting the member, said weld structure constituting said second effective bimetal pair.
 5. The apparatus defined by claim 3 wherein said first and second components are arranged mutually parallel but have at least a portion thereof orthogonal to said third and fourth components such that said bimetal means has a channel-like configuration.
 6. A suspension system for supporting a light-weight, frameless, rectangular color selection electrode adjacent the faceplate portion of a color cathode ray tube envelope, comprising four electrode suspension devices, one at each corner of the electrode, for supporting the electrode adjacent to said faceplate portion, each device comprisinG mask-mounted means affixed to said electrode which retentively engages envelope-mounted means affixed to said faceplate portion, said mask-mounted means including bimetal means having at least two edge-bonded components, said bimetal means, when heated, deflecting to produce two components of deflection motion - a first component which causes the suspended electrode to be displaced toward the faceplate along the central Z axis of the tube for Q compensation and a second component which at least partially compensates for thermal expansion of said electrode in an X-Y plane orthogonal to the Z axis so as to reduce build-up of expansion-induced stresses in the suspension system and in the electrode.
 7. The apparatus defined in claim 6 wherein said bimetal means comprises effective first and second orthogonally acting bimetal pairs, said first bimetal pair producing a deflection of the bimetal means such that it has a primary component of deflection motion in the Z direction, said second bimetal pair producing a deflection of a bimetal means such that is has a primary component of deflection motion in the X-Y plane.
 8. The apparatus defined in claim 7 wherein said bimetal means comprises a one-piece, sheet-like member having four strip metal components bonded together, a first and second component constituting said first bimetal pair and having different coefficients of thermal expansion and being edge-coupled in the plane of said member such that upon heating of said member, said first and second components produce deflection of the member in the plane of the member, said third and fourth components constituting said second bimetal pair and having different coefficients of thermal expansion and being face-coupled in the thickness dimension of said member such that upon heating of said member, said third and fourth components produce deflection of the member out of the plane of the member.
 9. The apparatus defined in claim 8 wherein said four components of said member comprise four discrete, mutually bonded metal strips, said third and fourth components being embraced by said first and second components.
 10. The apparatus defined in claim 7 wherein said first bimetal pair comprises first and second strip metal components having different coefficients of thermal expansion which are edge-bonded through an intermediate weld structure having a predetermined assymetry relative to a length-extending plane bisecting the member, said weld structure constituting said second effective bimetal pair.
 11. The apparatus defined in claim 9 wherein said first and second components are arranged mutually parallel but have at least a portion thereof orthogonal to said third and fourth components such that said bimetal means has a channel-like configuration.
 12. The apparatus defined in claim 6 wherein said device each comprise means for supporting said bimetal means which includes separate spring means affixed to said bimetal means.
 13. The apparatus defined in claim 12 wherein said spring means has a substantially constant stress vs. strain characteristic.
 14. The apparatus defined in claim 6 wherein said bimetal means comprises two coplanar, edge-bonded strips of metals having different coefficients of thermal expansion, said devices each including means for supporting said bimetal means with the plane of each of said bimetal means oriented at a predetermined angle relative to said Z axis such that said bimetal means, when heated, deflects in its own plane to produce said two components of deflection motion.
 15. A bimetal member for supporting a color selection electrode in a color cathode ray tube, comprising effective first and second orthogonally acting bimetal pairs, said first bimetal pair deflecting, when said member is heated, to produce in said member a primary component of deflection motion in a predetermined plane through the member, said second bimetal pair deflecting, when said member is heated, to produce in the member a primary component of deflection motion out of said plane.
 16. The apparatus defined by claim 15 wherein said bimetal member comprises a one-piece, sheet-like planar element having four strip metal components bonded together, a first and second component constituting said first bimetal pair and having different coefficients of thermal expansion and being edge-coupled in the plane of said element such that upon heating of said element, said first and second components produce deflection of the element in the plane of the element, said third and fourth components constituting said second bimetal pair and having different coefficients of thermal expansion and being face-coupled in the thickness dimension of said element such that upon heating of said element, said third and fourth components produce deflection of the element out of the plane of the element.
 17. The apparatus defined by claim 16 wherein said four components of said element comprises four discrete, mutually bonded metal strips, said third and fourth components being embraced by said first and second components.
 18. The apparatus defined in claim 15 wherein said first bimetal pair comprises first and second strip metal components having different coefficients of thermal expansion which are edge-bonded through an intermediate weld structure having a predetermined assymetry relative to a length-extending plane bisecting the member, said weld structure constituting said second effective bimetal pair.
 19. The apparatus defined by claim 16 wherein said first and second components are arranged mutually parallel but have at least a portion thereof orthogonal to said third and fourth components such that said bimetal means has a channel-like configuration. 